games on Arunrocks

Python One-liner Games

Sun, 22 Mar 2015 21:09:00 +0530

I took a break from the intense book schedule this weekend (don’t worry everything is on schedule). Was reading about Commodore’s one-liner maze when it struck me.

I wondered - why not make some one-liner games in Python? And just to make it insanely hard, I would try to make it fit a tweet i.e. 140 characters. Let’s see what we could manage.

NOTE: All the one-liners below work only in Python 3. Depending on your platform, you might want to change the code by replacing python with python3.

Maze

python -c "while 1:import random;print(random.choice('|| __'), end='')"

Create an infinite maze with this deceptively short one-liner. It is quite easy to understand too. The while loop is infinite. The import statement had to move inside the loop but Python takes care not to re-import it each time.

A random character is picked from one of the maze drawing characters and printed. An alternate version below has better maze drawing characters. But this version used characters which were displayable on the Windows shell (and possibly portable to other operating systems).

Prettier Version

python -c "while 1:import random;print(random.choice('╱╲'), end='')"

This version uses two Unicode characters. The maze walls look more connected in this version and the viewing angle is interestingly skewed.

If you are more interested in the history and phenomenon of these one-liner mazes, then I suggest you check out the book 10 PRINT, which can be freely downloaded.

Crash!

Crash is a homage to the BASIC era games like Lunar Lander. Watch an out-of-control spaceship fall into earth. You need to freeze time (i.e. Ctrl+Break) just before it hits the cliff walls.

python -c "while 1:locals().setdefault('i',60);import time,random;print(' '*i+'<>'+' '*(80-i-1)+'|');time.sleep(.1);i+=random.randint(-2,2)"

Once again, we rely on while to create an infinite loop. Since the whole code is wrapped in a loop, we cannot initialise the spaceship position i. Unless, of course, we setdefault the locals() dictionary directly.

The print statement pads spaces i times to offset the ship’s symbolic representation. Then a slight delay is introduced for a convincing animation and the ship’s position is randomly shifted left or right. This put together gives the mesmerising effect of a swerving ship.

Slot Machine

Back when we were kids, we had a handheld toy slot machine with plastic rollers. We used to love spinning it until the three 7s aligned and everyone used to yell - Jackpot!

python -c "import random;p=lambda:random.choice('7♪♫♣♠♦♥◄☼☽');[print('|'.join([p(),p(),p()]),end='\r') for i in range(8**5)]"

This is one of the most fun games here. Essentially it needs three independent random number generators. Using a lambda function was the obvious choice for the generator so that you could invoke it thrice.

I used a variety of fun-looking Unicode characters that rendered correctly even on a Windows shell. Using the \r (carriage return) terminator for print makes it overwrite the same line; giving the illusion of animation. Finally, 8**5 was chosen as a compact large number that completes looping in a reasonable time.

Slightly Longer Version

python -c "import random,time;p=lambda:random.choice('7♪♫♣♠♦♥◄☼☽');[print('[{}|{}|{}]'.format(p(),p(),p(),t=time.sleep(.1)),end='\r') for i in range(20)]"

This version is slightly more satisfying since you can actually see the symbols as they change. The printed representation is also slightly better. However, these changes made it exceed the length of a tweet.

100 Feet Golf

Inspired by Pingu Throw (and possibly Angry Birds), this game allows you to choose the angle and velocity of a golf ball. The objective is to make it fall exactly in a hole at the hundredth feet, no more no less.

python -c "import math as m;a,v=eval(input());[print('%03d'%x+' '*m.floor(0.5+x*m.tan(a)-x*x/(v*m.cos(a)))+'o') for x in range(102)]"

Entering the two values is slightly clumsy due to the length restrictions. You need to input a tuple having two numbers like (0.9,120) - the first number is the angle in radians and the second number is the velocity (in some arbitrary unit). Due to the use of the infamous eval statement and subsequent tuple unpacking, input in any other form will not work.

The remaining list comprehension is basically a for loop with a print function. The ‘height’ of the golf ball is calculated by a simplified form of the actual physics formula to compute projectile trajectories.

The range is chosen to be slightly more than, the expected, 100 to give an idea of the trajectory in case you overshoot.

Slightly Longer Version

python -c "import math as m;a,v=m.radians(float(input())),float(input());[print('{:03}:'.format(x)+' '*m.floor(0.5+x*m.tan(a)-x*x/(v*m.cos(a)))+'o') for x in range(102)]"

This version has a more sane method of entering values. The first input is the angle in degrees (thank god!) and the next input is the velocity. However, it exceeds the length of a tweet.

Number Guess

This is a classic game for new programmers. Rules are easy to understand - I am thinking of a number between 1 and 99. You can make a guess and I will tell if your guess is higher (‘H’) or lower (‘L’) than my number. You can make up to six guesses.

python -c "import random;n=random.randint(1,99);[(lambda a:print('Y' if a==n else 'H' if a>n else 'L'))(int(input())) for i in range(6)]"

Most of the techniques used here should look familiar - list comprehensions, lambdas and random integers. The lambda is needed since the input variable needs to be assigned (when the lamda gets called). The if else short form is used as a ternary operator.

Upon a successful guess the game prints a ‘Y’. However, it doesn’t stop which is a possible drawback of this implementation.

As you might know, the best strategy is a binary search. To make the game more interesting, I have chosen the maximum number of guesses to be one less than the ideal to span the range.

How to Write One-liners in Python?

One-liners are notoriously hard to write in Python. You would be hard pressed to find examples of one-liners with the exception of the Python wiki.

What makes it so hard? Well, there are a couple of reasons:

Whitespace-significance: This makes is quite hard to include block statements like while or for. Often the entire program is wrapped in one loop statement.
Verboseness: Unlike languages like Perl there are no short hand symbols say for commandline arguments or regular expressions

But Python is not devoid of merit for creating one-liners. Thanks to some great functional programming features it does have some advantages like:

Lamdas: Defining functions in a line does come handy despite its limitations.
List comprehensions: Readable yet terse constructs.
Reflectiveness: Ability to edits its own local variables for instance is quite handy.

Overall, I am quite surprised by the kinds of games I could manage. My daughter and I had lots of fun playing and tweaking some of these games. They are probably the most fun I could get from one line of code.

Atari and Gaming History

Mon, 30 Jan 2012 18:54:02 +0530

Imagine your 8 year old cousin, who is learning to use computers, asking you about the Save icon on Microsoft Word. The image of a floppy disk is almost universally used to denote ‘saving a file’. But with floppy disks gone, would the coming generation understand the symbolism?


I had the same problem with the joystick icon commonly used to denote Games. Typically it is drawn as a stick pointing up, protruding from a box. Most of the consoles that I was familiar with had much more elaborate game controllers or gamepads. However this simple black-coloured gaming device remained a mystery to me.

Until I read the book ['Racing the Beam: The Atari Video Computer System'][book] that is. I started reading this book out of curiosity and due to a certain interest in gaming history. But soon realised that it is a must-read for anyone interested in Game design or even the roots of Gaming culture. It covers not just the historical context of the Atari VCS and its popular games but some of its nearly impossible technical constraints.

[book]: http://www.amazon.com/gp/product/026201257X/?ie=UTF8&tag=arunrocks-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=B0015UC17E

One of the most amazing thing about Atari games were that they could use only 128 **bytes** of RAM. Yes you read that right. It is not Megabytes or even Kilobytes, I mean Bytes. To give you a better idea, I have italicised the first 128 characters at the beginning of this blog post. Yes, it is that small.

![Atari Flashback](/static/images/blog/atari-flashback.jpg)

To program an entire game with graphics, sounds and gameplay with several levels would seem impossible given such constrains. But remember that RAM refers to the working memory or the read-write area. Atari would store most of the game content in removable cartridges containing about 4 kB of ROM or Read Only Memory. Now, 4 kB is not much either. Today, even the smallest images, say an icon, would be bigger than that. Imagining packing an entire game in that space. Incredibly cool!

Constraints bring out some of the most creative solutions. There could be no better example of this than Atari games. Not only were Atari games enjoyed by millions of gamers, they also boast of many pioneering achievements. The 1979 game _Adventure_ is considered to be the first action-adventure game. One of the great grandfathers of games like _Warcraft_, the game allowed the player to explore multiple rooms with the ability to pick up, carry or drop items, a first at that point in time. It was also the first game to have a widely known 'Easter Egg.' 

_Yar's Revenge_, released in 1981, takes place in space and uses game code as game data. Taking place in space, the game screen is dominated by a striped randomly coloured neutral zone. Rather than use a random number generator, the game's creator brilliantly converted the game's own binary code into a psuedo-random pattern, saving precious ROM space. In other words, you are looking into the game's own code while playing the game. How many games have you played that can claim that?

Not all firsts mentioned in the book are technical innovations. It narrates how Atari employees broke off to start Activision, the first third party video game company. Of course, Atari's first game _Pong_ was a cultural phenomenon. Atari is also considered as the longest living game console spanning a duration of **14 years and 2 months** in US gaming history.

As a side note, if you have read [Steve Job's autobiography][steve] then you must be aware that Steve Jobs was Atari's fortieth employee. He was a technician paid at $5/hour. They sent him to India to help him do 'spiritual research'. Later it was their $100 bounty for each chip removed from the design of _Breakout_ that triggered Jobs to reach out to Steve Wozniak. Interestingly, they eventually offered Apple II to Atari and they were not interested. Imagine that, Atari could have actually bought Apple!

Today, one can still buy [Atari Flashback][flashback], a successor of the original Atarai 2600. It contains two of the iconic joysticks bearing a close resemblance to the original joysticks. There are many recent accounts of parents [rediscovering][rediscover] such legacy arcades. Small children don't seem to mind the simple graphics thanks to their active imagination. Adults also love the competitiveness of two-player games.

Sometimes to better understand the present, one needs to dive into the past. Knowing Atari's past was not only instructive but also inspiring.

[steve]: http://www.amazon.com/gp/product/1451648537/
[flashback]: http://www.legacyengineer.com/storefront/index.php?main_page=product_info&products_id=124 
[rediscover]: http://www.codinghorror.com/blog/2008/04/rediscovering-arcade-nostalgia.html

This is a Game. There are rules

Wed, 07 Dec 2011 21:49:52 +0530

I have been recently reading a book on game design that primarily focuses on non-digital games. It is called Challenges for Game Designers. It distills the art of game design to using easily available materials like paper, dice or playing cards. They call it a non-digital approach.

We have all played such games at some point in time. Before video games, as kids, we used to play snakes and ladders or chess. In Kerala, we have several indoor games using easily available materials like pebbles, cowries (kavadi in Malayalam), circassian seeds (manjaadi in Malayalam) and irkili sticks (stiff mid-ribs of coconut leaves). The rules were simple - say, remove the smallest stick without disturbing others or align the seeds in a row. These ‘eco-friendly’ and ‘low-cost’ games used to provide hours of fun to children and adults.

Compared to modern video games these games lack high production values marked by hundreds of detailed 3d modelled characters and unfolding of several hours worth of intricate plots and storylines. These traditional games don’t have any stories, they are mostly tests of skill or chance. They were fun interactive experiences fuelled by imagination.

What’s wrong with my digital game?

The biggest advantage board games have is the trust factor. They exist in a familiar world - the real world. A world with familiar laws of physics and hence predictable outcomes.

Whereas a digital world is essentially a make-believe world created by the game designer. It may or may not follow the rules of the real world. If you touch this strange flower, it might wobble or it might balloon into a giant carnivorous plant. You are not quite sure. If the game designer did not leave tell-tale signs on the flower, the only way to find out is to risk touching it.

To players who are adventurous, this sounds like fun. After all, exploration in a safe world ought to be a fun experience. But you cannot leverage all the experience you had in the real world (which certainly took you several years) into this new world immediately. It is an alien environment and you must invest some time in getting familiar. Even then, there is always an element of Deus ex machina lurking the dark crevices of a digital game.

Board games on the other hand involve familiar or even everyday objects to create experiences which are much greater than sum of its parts. A token on the board will not mutate into something else if you move it to the next square on the board. Nor will it affect the real world you are playing in (unless you are playing Jumanji ).

This principle of least surprise primes you to play the actual game once you finish explaining the game’s rules. Unlike a typical video game, there is no unneeded exploration to get a feel of the environment. In other words, you don’t need to learn to stand up before you can start running.

Another great advantage these non-digital games have is the ease of modifying them. Changing a fundamental game rule such as whether you can use the joker in pack of cards requires just a simple consensus between players. The game rule changes and, in turn, changes the game experience.

On the other hand, a digital game is built using programming tools which in turn builds a rigid mathematical model of the game world. The rules and character behaviours are generally fixed. With the exception of a few games like SimCity or Minecraft, free-style play is discouraged in favour of a mission-oriented game design. For instance, you cannot turn a fire-breathing dragon into a pet.

Rise in popularity of the game-modding community however highlights the desire to do so. Thousands of enthusiasts who like to customise their game experiences from tweaking a game character’s face to reprogramming the enemy AI behaviour enjoy playing and sharing these modifications. However, these modding tools have steep learning curves and need considerable investments in time and effort.

What’s right with my digital game?

What digital games sometimes lack in content is often made up in presentation. Colorful and animated worlds are often the hallmark of digital games. The latter aspect i.e. animated movement is a key element for explaining their appeal.

Computer games and in fact TV screens appeal to the T-Rex part of our brains. This reptilian cohabitant gets easily mesmerised by rapid movements and flashy lights. It expects something essential to survival to happen when there might be none. It is simply a trick on our evolutionary instincts. However, the trick doesn’t work for long as a boring game will not sustain continued interest.

Nevertheless, this initial impression gives digital games an edge over traditional games. A well designed digital game might be more appealing than a well designed board game, especially to young adults.

Digital games also enjoy the advantage of easy distribution. Even within the PC game industry, digital distribution by online purchases is overtaking retail sales of boxed games.

Once made available on the internet, a digital game becomes universally available and ready to play once setup. On the other hand, even if a board game is made free to print-and-play, it takes a lot of cutting and setting up to start playing.

In addition, non-digital games with extensive rules requires someone to read and understand all the rules even before the play begins. Even then, some of the rules might be missed or misinterpreted by an inexperienced player.

The rigidness of the digital game’s world avoids all these pitfalls. The game world is setup as soon as you begin playing and the rules being inviolable can be learnt by exploration. This lowers the barrier of entry to start enjoying the game.

This is a crucial advantage to a causal player who would like to start playing the game as soon as possible rather than get involved in the formalities of learning the game.

Can we have the best of both worlds?

We can certainly imagine a marriage of both worlds - digital and non-digital games. The digital avatars of typical board game like Chess or Cluedo attempt to do just that.

They offer the convenience and packaging of a digital game, yet they use familiar game objects like dice or tokens. However, the end result might not always be well executed. The entire user interface needs to be as intuitive as a board game. Often touch screens like iPads are a good platform for such hybrid games. However, the flexibility of a board game inevitably loses when it enters the rigid world of digital games.

In conclusion, board games are an invaluable legacy that imparts a lot of fun with familiar objects. But would the legacy survive the onslaught of digital revolution in its present form? Or will it evolve into a hybrid variation of both? Only a throw of the dice can tell :)

PS: The headline is paraphrased from a dialog in the cult-classic film The Big Lebowski (1998), “Smokey, this is not ‘Nam. This is bowling. There are rules."

Mario Touches Silver Jubilee

Wed, 15 Sep 2010 01:40:39 +0530

You were merrily hopping through a lush green garden when you notice a giant grey pipe sticking out of the ground. Always ready for some action, you leap into the pipe without a second thought. You fall into a dimly lit underground passage. As you look up, you notice the sparkling gold coins hanging in the air. You realise there are probably hundreds of them. You can barely contain your excitement as you jump to pluck as many coins from the air.

Dreams in our childhood were sometimes made of episodes such as these. All thanks to extended bouts of playing Mario on our TV screens. The adorable plump plumber turns 25 this week. However, he is as fit as ever as one would notice from his acrobatics in his latest game ‘Super Mario Galaxy 2’. Mario and his sidekicks like Wario, Lugi and Pauline have appeared in over 200 titles over these years. This is a testament to Nintendo’s vision and innovation in creating the game industry’s first Superstar.

There have been various funny variations of one of the world’s most popular game title - Super Mario Bros (240 million in lifetime sales and still selling!). One game designer’s resignation letter was a Mario game titled ‘A Message for 2K Australia’ (his employer)! A geek proposed to girlfriend inside a Mario-like video game by spelling out the words “Lisa Will You Marry Me?” using gold coins. There are several other instances of Mario fans creating a 8-bit wedding invitation game to an entire room designed after Mario’s colourful world.

Evergreen Mario

There are no signs of Mario retiring atleast for the immediate future. Whatever be tomorrow’s technology be it 3D or full body motion sensors, you can expect Mario to be there and kicking some posteriors! :)

Disclaimer: Mario and all related characters and elements are copyrighted to Nintendo